1. Origin of the Invention
The present invention was developed with funding from the Electric Power Research Institute (EPRI) of Palo Alto, Calif., Grant No. RP 8002-30.
2. Field of the Invention
The present invention concerns an electrode design which incorporates a porous surface layer of an electrolyte material over a dense electrolyte and introduction of an electrocatalyst into the porous layer such that the electrocatalyst also is continuous. Thus, the resulting electrode structure consists of: 1) a continuous electrolyte (porous); 2) a continuous electrocatalyst; and 3) a continuous gas phase. This type of electrode structure enhances the three phase boundary (TPB) length between electrocatalyst, electrolyte, and gas phase where the charge transfer occurs as compared to conventional electrode designs. Although the path length through the electrolyte is increased, the overall area specific resistance is decreased as a result of the enhanced TPB length. In solid oxide fuel cells, this design leads to a lowering of the area specific resistance by more than a factor of two. This design leads to a substantial increase in the current and power densities that are achieved in the state-of-the-art solid oxide fuel cells (SOFCs). The new design also allows the operation of SOFCs at a lower temperature (800.degree. C. vs. the current 1000.degree. C.). Lower operation temperature means lower cost of materials and fewer problems related to oxidation and corrosion.